Method and apparatus for handling and burning coal slurries



J. JONAKIN April 11, 1967 METHOD AND APPARATUS FOR HANDLING AND BURNING COAL SLURRIES Filed Dec. 15, 1961 2 Sheets-Sheet l INVENTO R JAMES JONAK I N ATTORNEY April H, 1967 J. JONAKIN METHOD AND APPARATUS FOR HANDLING AND BURNING COAL SLURRIES Filed Dec. 15, 1961 2 Sheets-Sheet 2 FIG-2 W 1. r N 2 a Z 4mg W M 05 M j a 2 y E w A v M z W I? Al H m K Y W W Tw 3% v mu m M A J United States Patent Ofifice 3,3l3,25l Patented Apr. 11, 198? MEailfiD AND APPARATUS FOR HANDHNG AND BURNING CQAL SLURREES James .lonaltin, Simshury, Conn, assignor to Combustion Engineering, Inc, Windsor, (101111., a corporation of Delaware Filed Dec. 15, 1961, Ser. No. 159,603

11 Claims. (ill. 11ll7) This invention relates generally to the handling and burning of coal and has particular relation to an improved method and apparatus for utilizing pipeline coal slurry as a source of heat particularly for firing Vapor generators equipped with cyclone furnaces.

Co-pending application Ser. No. 521,238 of Jonakin and Tulis filed Dec. 20, 1965 and which is a continuation of application Ser. No. 159,600 filed Dec. 15, 1961 shows and broadly claims feeding, dewatering and flocculating method and apparatus for pipeline coal.

An object of this invention is to eficiently utilize pipeline coal slurry in a firing system employing cyclone firmg.

Another object of the invention is to provide an improved process and system for handling and burning fuel utilizing pipeline coal slurry and wherein the slurry is dewatered and then fired in a cyclone furnace.

Other objects and advantages will be apparent from the following specification and the accompanying drawings in which:

FIG. 1 is a schematic side elevation of a preferred embodiment of the invention showing the system for handling and preparing the coal slurry and for firing the coal into a cyclone furnace;

FIG. 2 is a schematic illustration, in the nature of a flow sheet, showing a system employing multiple cyclone furnaces each with its own slurry preparing unit; and

FIG. 3 is a modification of the system of FIG. 1 wherein a vacuum filter dewatering unit is utilized in lieu of the centrifuge shown in the FIG. 1 illustration.

In the supplying of coal from a source to a distant coal utilizing facility, such as from a mine to a vapor power plant installation, it has been found that the coal can be transported long distances by forming a slurry of water and crushed coal and pumping the slurry through a pipeline. The consistency of the slurry depends upon a number of factors. It is, however, desired that there be as small a percentage of water in the slurry as is practicable from the pumping and handling standpoint. A slurry of 50 percent coal and 50 percent water with the coal being crushed so that the coarse fractions are approximately one-quarter inch can be satisfactorily pumped through a pipeline over long distances. By crushing the coal to a somewhat smaller size, a 60 percent coal and 40 percent water slurry may be satisfactorily pumped, this is currently about the limit of coal concentration in water slurry that can economically be pumped through a pipeline over long distances. A relatively recent development indicates that still more concentrated coal-water slurries may be pumped through pipelines over relative short distances, such as a few miles, with a slurry wherein the coarse fractions are somewhat less than one-eighth of an inch being purnpable in a 70 percent coal and 30 percent water slurry and with indications being that this concentrated slurry is more stable with regard to settling, i.e., requires a longer time for the coal to settle out, than the previously identified slurries and with this being a very desirable property in that it makes the slurry much less difiicult to handle.

While the concentration of the crushed coal and water slurry may vary as explained hereinbefore, it remains within the bounds, in accordance with the invention, within which there is produced a slurry that may be satisfactorily and economically pumped through a pipeline. The greater the percentage of water that is pumped the less economical the process because the water is merely a carrier which must be eliminated in some manner at the location Where the coal is utilized for burning. Thus a slurry wherein the water content is greater than the 50 percent is not economically feasible. On the other hand, the concentration of coal in the slurry must be sufiiciently dilute so that the slurry can be pumped and handled satisfactorily. As previously mentioned, a concentration of 60 percent crushed coal and Water has been indicated to be a pumpable slurry which may be economically pumped over long distances while a slurry with a crushed coal concentration of 70 percent has been indicated as pumpable over short distances. These coal slurries to which reference is being made are comprised of crushed coal and water with crushed coal being a term that is well known and has long been used in the coal and fuel handling art. Crushed coal is distinguished from pulverized coal in that in the crushed coal relatively large or coarse coal fractions are present, with the crushed coal, as a result of the action of the crusher, containing particle sizes which range from the coarse fractions on down to very fine particles known as fines. Pulverized coal in contrast is a powder with all the coal being reduced to very fine particles through the action of a pulverizer.

In firing systems employing cyclone furnaces, crushed coal may be fed directly to and burned in the cyclone furnace, and notwithstanding the relatively high percentage of moisture in the coal-water slurry previously discussed and which is pumpable over long distances through a pipeline this crushed coal slurry may be introduced directly into the cyclone furnace and burned. The economics of such a system are not attractive, however, because this relatively large moisture content must be evaporated and conveyed through the vapor generator and out the stack causing a material heat loss which reduces the boiler etficiency from a possible 88.1 percent obtainable in a normal operation with 9 percent moisture bituminous coal to an efiiciency of 83.0 percent. At present day prices this represents about 43 cents a ton above the base price of the coa In accordance with the present invention this loss in eificiency is substantially reduced by reducing the water content in the slurry prior to feeding the crushed coal to the cyclone furnace with the dewatering being effected through mechanical actions and not through the application of heat to the slurry to drive off the water or a portion of the Water. By means of mechanical dewatering, the Water content of the slurry may readily and economically be reduced to a concentration of below 25 percent. While various methods and means for mechanically dewatering the slurry may be employed, the arrangement presently found preferable, taking into account capital cost, operating cost, dependability, capacity, and other factors, utilizes a solid state centrifuge wherein the slurry is centrifuged, with dewatered slurry having a water content of about 20 percent being produced. By de- Watering the slurry that is introduced into the cyclone furnace so that it contains only 20 percent moisture the efficiency of the vapor generator becomes 86.2 percent or greater and the increase in fuel cost over that of normal operation with 9 percent moisture coal is 16 cents or less a ton above base cost of fuel at present day prices.

In the system depicted in FIG. 1 the centrifuge mechanical dewaterer is utilized and in this system, as illustratively disclosed, a pumpable slurry of crushed coal and water is received through pipe ll) feeding a storage tank 24) which may be of any required size or number depending upon the storage requirements of the particular coal burning plant. The slurry is pumped by a pump 22 from the tank 2%, through a control valve 24, past a flow meter 26, such as a magnetic fiow rneter, through a shut-off valve 23 and a pipe 29 into a hopper 30. As will be described later this hopper 30 also receives flocculated fines. The contents of hopper 39 are fed by gravity or may be pumped by a pump, not shown, to a centrifuge indicated generally at 32. This centrifuge which may be a standard commercial article such as the centrifuge manufactured by the Bird Machine Company and comprises a hollow cone frustrum 34 adapted to be rapidly rotated as by a motor and having a substantially imperforate outer surface except for discharge openings 33 at the small end of the frustrum and having closed ends except for a discharge opening in the large end 40 spaced inwardly from the outer surface of the frustrurn and an opening in the large end 40 at the axis of the frustrurn for receiving slurry, from the tank 30. A casing 42 surrounds the rotating frustrum and contains one or more partitions dividing the casing into two discharge chambers one of which discharges into duct 44 and the other into receiver 46 and pipe 48.

The slurry discharged into the interior of the frustrum collects at the large end as it is thrown out by centrifugal force. A screw conveyer, not shown, cooperates with the interior of the frustrum as the frustrum rotates relative to the screw conveyer to force coal from the large end towards the small end of the frustrum where it is discharged through the orifice 38. Water being lighter than the coal will tend to stay nearer the axis of the centrifuge and will be discharged through the orifices in the end 40 of the frustrum. The coal which still may contain 20 percent or a little less of moisture, is discharged with considerable force from the orifice 38 and is forced down the duct 34 by this discharging force and by gravity into the cyclone furnace 49 which may be of the nature disclosed in US. Patent 2,357,301 issued Sept. 5, 1944.

Preheated air, acting as the primary combustion supporting air, is introduced into duct 44 from the conduit 51 and this air together with the stream of mechanically dewatered crushed coal is introduced into the cyclone furnace 49 at the inlet 53 with this inlet being tangentially arranged and preferably in the form of a volute and With the introduction of the primary air and the crushed coal being at such a velocity as to cause the particles of coal to be thrown outwardly toward the wall of the cyclone furnace. The furnace proper is of cylindrical configuration with the walls being formed by fluid cooled tubes which are studded and are covered on the inner side by a high temperature refractory material. Secondary air is admitted into the cyclone furnace through the tangentially arranged inlet 55 which directs this secondary air stream in the same direction of rotation as the fuel and air admitted through the inlet 53. The crushed coal is burned in the cyclone furnace and the temperature in this furnace is maintained above the fusion temperature of the ash in the coal so that liquid slag is produced which clings to the walls of the furnace. The crushed coal as it is supplied to the furnace and is thrown outward to the cylindrical walls thereof is caught in this layer of molten slag and as a result of the scrubbing action of the high velocity air over these coal particles cornbustion of the crushed coal in the cyclone is produced. The centrifugal action produced in the cyclone causes the slag to be disposed and retained on the furnace walls with the slag flowing out of the opening 57 provided in the rear wall of the cyclone and adjacent the lower region thereof, this slag being collected in the bottom of the refractory lined primary furnace 51 and discharged through an opening therein to a suitable ash handling system.

Combustion gases pass from the center of the cyclone through the collar 59, which extends inwardly from the rear wall of the cyclone, with these gases passing into the primary furnace of the vapor generator and thence up to the secondary furnace 49 and then through suitable gas 4 passes which contain the heat exchange surfaces conventionally found in vapor generators.

The primary and secondary furnaces have fiuid cooled tubes, such as vapor generator tubes, disposed in side-by side relation along their walls with these tubes being represented as tubes 61 and with there being a high temperature refractory material lining the surface of the primary furnace. The vapor generator which is shown only in fragmentary form in the FIG. 1 illustration and is identified generally as 63 is effective to produce vapor at a desired pressure and temperature. This vapor may be supplied to a suitable user such as turbine 65 through the supply conduit 67 with the delivery of the vapor to the turbine 65 being controlled through a suitable device 69.

The eifiuent discharged from the large end of the frustrum of the centrifuge 32 contains a considerable quantity of fines which are carried along with the water from the centrifuge, which may be 2 to 6 percent of the total contents of the coal in this slurry. It is necessary to recover these fines both because the dirty water cannot be discharged into a water reservoir or stream and second because these fines represent a material heat value. The efiluent containing these fines is fed through pipe 48 and is mixed with a fiocculating agent fed from tanks 72 through pipe 74 into pipe 48. This fiocculating agent may be any of the well known commercial fiocculating agents such as Separan sold by Dow Chemical Company, Midland, Michigan. The treated efiluent is fed to a clarifier or settling tank 76 where the fiocculating agent serves to flocculate or coagulate the fines or coal dust into larger particles which settle out in the bottom of the storage tank. The clear water then overflows into a receptacle 78 from which it is discharged into a lake or reservoir. The flocculated fines or coal fiocs which have collected in the bottom of the tank '76 are led through pipe 80 through a constant volume pump such as a gear or screw pump 82 and fed back through line 84 to a hopper 30 at the entrance to the centrifuge 32.

The efiluent fed back to the hopper 30 contains approximately 30 percent fiocculated fines and percent Water and is mixed with the slurry being fed from the tank 20 and fed to the centrifuge 32. In the centrifuge the fiocculated fines do not break down and are not again carried out with the etfiuent but remain as particles large enough to be fed by the screw conveyer in the contrifuge 32 and are discharged into the chute 44 along with the rest of the filter cake discharged from the centrifuge.

It will be noted that all of the filter cake discharged by the centrifuge 32 is fed directly to the furnace so that the control of the slurry fed to the centrifuge controls the quantity of coal supplied to the furnace. The magnetic flow meter 26 measures the flow of slurry to the centrifuge and a condition of the vapor generator such as pressure, temperature, or load demand, determines or regulates the fuel or slurry quantity desired in a manner well known in the art, such as that shown in US. Patents 2,530,117 or 2,538,428 with pressure responsive device 71 being illustratively disclosed as the condition responsive member. The fuel quantity as measured by the flow meter 26 is compared with the fuel quantity necessary to maintain the selected boiler condition and any variation between the two is utilized to operate the valve 24 to change the flow rate to correspond to that called for by the vapor generator condition. As the quantity of effiuent discharged by the centrifuge 32 will vary directly with the quantity of slurry supplied to the centrifuge, the speed of the motor 86 driving the pump 82 is varied in accordance with the opening of the valve 24 so as to maintain the same proportion of effluent returned for each position of the valve 24. The controls for the several control valves and motors may be assembled at a control panel 91.

While the preferred form of mechanical dewatering device is a centrifuge, as shown in FIG. 1 and previously described, other known types of mechanical dewatering mechanisms may be utilized, such as vacuum filters, with FIG. 3 being a representation of such a filter substituted in the system of the invention for the previously described centrifuge. The vacuum filter mechanism comprises a hollow drum 75 rotated about its axis at a desired speed by drive motor 77 and having a vacuum applied to its interior through the conduit 79, vessel 81 and vacuum pump 83. The drum 75 is partially immersed in a bath or reservoir of slurry contained in the chamber 85 with this slurry being supplied through the supply conduit Stla from the hopper 30. The hollow drum has fine perforations in its surface or is made of fine mesh material and as it rotates through the bath of slurry, the vacuum at the interior of the drum acts to hold the slurry against the outside of the drum surface and draw the slurry out of the bath. As this portion of the drum rotates in the air above the slurry bath the differential pressure resulting from the drum interior vacuum causes the water to pass from the slurry to the interior or inside of the drum with this water being sucked or removed through the conduit 79 and with this water efiluent, as in the case of the water effluent from the centrifuge, containing an appreciable amount of coal fines. As the slurry which is retained on the drum surface approaches the bath again, knives or scrapers are effective to scrape the now partially dry slurry from the drum and direct it onto the upper run of the continuous conveyer belt 89. This conveyer belt delivers the partially dried or dewatered crushed coal to the upper end of duct 44 and with the coal being conveyed down through this duct and together with primary air being introduced at high velocity into the cyclone furnace. The water efiiuent from the vacuum filter is collected in the sump 87 from which it is conveyed through conduit 48a to the clarifying tank 76 with a flocculating agent being added to this effluent as it is conveyed through the conduit 48a in the manner previously described. Coal flocs from the clarifying tank 76 are returned through conduit 84 to the hopper Si) in the manner explained with regard to FIG. 1.

In the organization of the invention each cyclone furnace has its own separate mechanical dewatering mechanism with the supply of coal to the furnace being controlled by controlling the supply of slurry to the mechanical dewaterer. This cyclone furnacedewatering mechanism comprises what may be termed a unitized organization or system. In the preferred arrangement disclosed in FIG. 1 as well as the modified organization of FIG. 3 there is provided a fiocculator for the efiluent of a single mechanical dewatering device. It will generally be desired, however, that a vapor generator be provided with more than one cyclone furnacemechanical dewatering unit and in such case a single flocculator may be employed to serve all or at least several of these units with the efiluent from the several mechanical dewaterers being conveyed to one fiocculator. Such a plural cyclone furnace-mechanical dewaterer system is diagrammatically represented in FIG. 2. In the system thus shown the slurry of crushed coal and water is fed to the tank 29 from the pipeline 10. A branch line 12 may be provided for directing excess slurry to a storage reservoir for storing as slurry or to a drying plant where the slurry may be dried by a flash drying process and then stored as crushed coal. The slurry is pumped by the pump 22 through line 83 to a manifold 99. The several unitized systems each receive their proportion of the slurry through individual pipelines controlled by individual control valves 24a, 24b, 24c, and 24d. Each valve con- -trols the flow to its respective centifuge in accordance with the vapor generator condition as previously described. These valves may be constructed to operate in unison from a single set of signals or may be constructed to operate individually from the error signal provided by the vapor generator condition. If the valves are in dividually controlled each flow meter signal would be individually corrected by its respective control valve which is controlled by the error signal indicating a variation of the generator condition from the desired condition while if they are all controlled in unison the sum of the individual flow signals would be compared with the error signal. The flow meter is not shown in FIG. 3 but would be located as shown in FIG. 1 between each control valve and its respective centrifuge. Each centrifuge 32a, 32b, 32c, and 32d feeds its respective cyclone furnace 49a, 4%, 49c, and 49d in the manner previously described and as shown in FIG. 1. In order to maintain a constant head across the several valves 24a, 24b, 24c, and 24d, excess slurry is fed from the manifold 9% through a pipe 92 to a tank 94 arran ed at a suitable level say 20 feet above the valves to thus maintain a static head on them. Excess slurry is returned through the pipe 26 back to the slurry tank 2% by means of a pump 98 which may be controlled in any suitable manner to maintain the level in the tank 94. Efiluent from the several centrifuges are led through the pipes 48a, 4811, 4dr, 48d to a manifold 10%) and thence back to the fluocculating and clarifying tank 76. The fluocculating agent not shown in FIG. 2, may be added in any suitable manner such as introduced into the pipeline between the manifold 1G0 and the tank 75. The fiuocculated fines are returned through the line 84 back to the slurry tank 20.

It should be noted that in FIG. 2 instead of returning the fluocculated fines to the individual centrifuge they are returned to the slurry tank where they are mixed with the incoming slurry so that the pump 22 of the FIG. 2 construction does not have a direct effect on the centrifuge intake and may if desired be controlled by any desired condition such as the condition of the tank 7s and not be dependent on the several valves 24.

From the above-identified description it will be apparent that with the present invention there is provided a method and organization wherein a pumpable Water slurry of crushed coal is employed as the fuel source for a fuel burning organization employing a cyclone furnace or furnaces. With the organization and process of the invention a substantial higher efficiency is obtained than would be had if the slurry would be introduced directly into the cycle and at the same time the process and system of the invention is economic as well as being dependable in its operation.

What is claimed is:

1. The method comprising delivering to a liquid extraction zone at a controlled rate crushed coal in a slurry purnpable through a pipeline, mechanically extracting a substantial portion of the liquid from said slurry at said zone and sufiicient to produce a mechanically separated coal stream having less than 25 percent Water, continuously and directly delivering this coal stream as mechanically separated to a cyclone furnace and burning the same therein, generating vapor by the heat evolved by burning said fuel and regulating the rate of delivery of slurry to the liquid extraction zone proportional to the load demand for the vapor.

2. The method comprising delivering to an elevated mechanical liquid extraction zone at a controlled rate crushed coal in a slurry pumpable through a pipeline, mechanically extracting a substantial portion of the liquid from said slurry at said zone and sufficient to produce a mechanically separated coal stream having less than 25 percent liquid, continuously forcing the coal stream as mechanically separated from said mechanical liquid extraction zone through the action of said mechanical extraction and through the action of gravity directly to a cyclone furnace at a lower level and burning the coal therein, generating vapor by the heat evolved by burning said fuel and regulating the rate of delivery of slurry to the liquid extraction zone proportional to the load demand for the vapor.

3. The method of handling and burning coal comprising providing a water slurry of coal, crushed to a size such that the coarse fractions are not over one-quarter inch and preferably slightly less than one-eighth inch, with sufficient water so that the slurry may be readily pumped through a pipe, delivering this slurry to a dewatering zone and thereat mechanically dewatering the same, separating water from the coal and creating a stream of mechanically dewatered coal having less than 25 percent water and a stream of separated liquid containing coal fines, delivering the dewatered coal directly from said zone to a cyclone furnace and burning the same therein, flocculating the coal fines in said separated liquid only and admitting the coal fiocs along with said slurry to said dewatering zone.

4. The method of handling and burning coal comprising providing a water slurry of coal, crushed to a size such that the coarse fractions are not over one-quarter inch and preferably slightly less than one-eighth inch, with sufiicient water that the slurry may be readily pumped through a pipe, delivering this slurry to a dewatering zone and thereat mechanically dewatering the same, separating water from the coal and creating a stream of mechanically dewatered coal having less than 25 percent water and a stream of separated liquid containing coal fines, delivering the dewatered coal directly from said zone to a cyclone furnace and burning the same therein, flocculating the coal fines in said separated liquid only and admitting the coal fiocs along with said slurry to said dewatering zone, generating vapor by the heat evolved by burning said fuel and regulating the rate of delivering of slurry and coal fiocs to the dewatering zone in accordance with the generation of vapor.

5. The system comprising transporting coal from a source by pumping the same in a confined stream comprised of a pumpable slurry of crushed coal and water to a site for use, pumping at said site at least a portion of said stream to a dewatering zone and thereat through the action of mechanical forces separating sufficient water from the slurry to produce coal having a moisture content of less than 25 percent and of approximately percent, and conveying this mechanically dewatered coal directly to and burning the same in a cyclone furnace.

6. The method of preparing and burning coal comprising pumping a stream of crushed coal in a water slurry to a mechanical dewateriug zone, applying mechanical separating forces to said slurry at said zone thereby separating water from the mixture, continuously delivering all of said dewatered coal directly from said mechanical dewatering zone to a confined volume together with preheated air and burning the coal therein while imparting a cyclonic motion thereto and while maintaining the temperature therein above the fusion temperature of the ash in the coal, generating vapor by the heat evolved by burning said fuel and regulating the rate of delivery of slurry to the liquid extraction Zone proportional to the load demand for the vapor.

7. In a coal handling and burning system the combination including means through which a pumpable slurry of crushed coal and water is conveyed, mechanical dewatering mechanism receiving slurry from said means and operative to dewater the coal by removing water from the slurry so that it contains only approximately 20 percent moisture, a cyclone furnace and means operative to convey the mechanically dewatered crushed coal with the approximately 20 percent moisture directly from the mechanical dewatering mechanism to said cyclone furnace for burning therein.

8. The combination of a source of pumpable slurry of coal and water, mechanical separating means receiving said slurry and operative to separate the same into an effluent of water and coal fines and partially dewatered slurry containing not more than percent water, a cyclone furnace means at an elevation lower than said mechanical means, means directing the mechanically dewatered slurry downward from said mechanical means directly to said furnace means for burning therein, a flocculating device operative to receive only said effluent and a flocculant and flocculate the fines, and means returning the fiocs to said mechanical means.

9. The combination of a source of pumpable slurry of coal and water, mechanical separating means receiving said slurry and operative to separate the same into an effluent of water and coal fines and partially dewatered slurry containing not more than 25 percent water, a cyclone furnace means at an elevation lower than said mechanical means, means directing the mechanically dewatered slurry downward from said mechanical means directly to said furnace means for burning therein, means regulating the supply of slurry to the separating means to regulate the rate of fuel fed to the furnace, a system receiving a portion of the heat energy evolved in the furnace and means forming part of said system for controlling the slurry regulating means.

10. In a fuel handling and burning system the combination of means for conveying a pumpable slurry of crushed coal and water, a centrifuge receiving slurry from said means, a cyclone furnace receiving dewatered coal directly from said centrifuge for burning therein, means for regulating the supply of slurry to the centrifuge to control the rate of fuel delivery to the furnace and means effectively responsive to the heat evolved by burning fuel in the furnace for controlling the slurry regulating means to provide a rate of fuel delivery proportional to the demand for heat.

11. In a fuel handling and burning system the combination of vacuum filter, means supplying to said filter a pumpable slurry of crushed coal and water, a cyclone furnace receiving dewatered coal directly from said filter and within which it is burned, a flocculating device re ceiving the water effluent from the filter to fiocculate the coal fines therein independent of said pumpable slurry, and means returning the coal fiocs to said filter.

References Cited by the Examiner UNITED STATES PATENTS 1,472,931 11/ 1923 Morison.

1,887,177 11/1932 Adams 210-519 2,246,224 6/ 1941 Streander 210-195 X 2,346,151 4/ 1944 Burk 44-1 2,357,301 9/1944 Bailey et a1. 122-336 2,530,117 11/ 1950 Dickey 23 6-26 2,538,428 1/ 1951 Sawyer 236-14 2,597,230 5/1952 Davis 210-73 X 2,648,950 8/1953 Miller 60-39.46 2,685,369 8/ 1954 Crossley.

2,725,145 ll/1955 Mylius 210-402 2,856,872 10/1958 Steinert -106 2,905,116 9/1959 Sifrin et al 110-28 2,920,923 1/ 1960 Wasp et a1. 302-66 3,124,086 3/1964 Sage et al 110-7 OTHER REFERENCES Separan 2610 in the Coal Industry-Published in April 1956 (Revised June 1956) by the Dow Chemical Company, Midland, Michigan (19 pages).

FREDERICK L. MATTESON, 1a., Primary Examiner.

PERCY L. PATRICK, JAMES W. WESTHAVER,

Examiners.

C. B. DORITY, H. B. RAMEY, Assistant Examiners. 

7. IN A COAL HANDLING AND BURNING SYSTEM THE COMBINATION INCLUDING MEANS THROUGH WHICH A PUMPABLE SLURRY OF CRUSHED COAL AND WATER IS CONVEYED, MECHANICAL DEWATERING MECHANISM RECEIVING SLURRY FROM SAID MEANS AND OPERATIVE TO DEWATER THE COAL BY REMOVING WATER FROM THE SLURRY SO THAT IT CONTAINS ONLY APPROXIMATELY 20 PERCENT MOISTURE, A CYCLONE FURNACE AND MEANS OPERATIVE TO CONVEY THE MECHANICALLY DEWATERED CRUSHED COAL WITH THE APPROXIMATELY 20 PERCENT MOISTURE DIRECTLY FROM THE MECHANICAL DEWATERING MECHANISM TO SAID CYCLONE FURNACE FOR BURNING THEREIN. 